Bonding pad structure

ABSTRACT

A substrate has a bonding region and a sensing region. A first dielectric layer is formed overlying the substrate and has a dielectric island surrounded by a ring-shaped trench. A first conductive layer is formed in the ring-shaped trench of the first dielectric layer. A passivation layer is formed overlying the first dielectric layer and has an opening, in which the opening corresponds to the bonding region and the sensing region and exposes the dielectric island and a part of the first conductive layer. A second conductive layer covers the opening of the passivation layer and is electrically connected to the first conductive layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. patent application Ser. No.10/696,186, filed Oct. 29, 2003, now U.S. Pat. No. 7,057,296 B2.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to integrated circuits, and more particularly to abonding pad structure.

2. Description of the Related Art

Bonding pads are interfaces between integrated circuits contained insemiconductor chips and a device package. Modern IC designs with highcircuit density require a significantly increased number of pins andbonding pads to reduce bonding pad pitch and size. Large mechanicalstresses inherent in bonding operations, however, easily damage smallerbonding pads.

Traditionally, each bonding pad is connected to one or more contact padson an IC-mounting surface of the device package through wire-bonding,tape automated bonding (TAB) or flip-chip technologies. When an IC chipis probed in an electrical test or the like, a probe pin may damage thesoft surface of the bonding pad. The Cu layer beneath the AlCu pad isexposed to air, and may be corroded. The corroded pads caused by thistype of pad voids degrade the bondability of wire connection. Currently,a top copper layer of a solid profile is used for connecting an aluminumpad, but has disadvantages of pad voids, narrow bondability window, balllifting and dielectric crack issues. Accordingly, several modificationsof the top copper layer have been developed as listed below. Moreover,in order to overcome this problem, the bonding pad has been divided intoa bonding pad region and a sensing pad region, and the probe pin isbrought into contact only with the sensing pad region which is allowedto be damaged.

As disclosed in U.S. Pat. No. 6,552,438, one conventional bonding padcomprises a plurality of independent metal plugs formed in an array ofvia holes of an inter-dielectric layer, in which each metal plug has abottom portion connected to a lower aluminum layer and a top portionconnected to an upper aluminum pad. Moreover, a passivation layer isformed on the aluminum pad to expose a predetermined bonding area forbonding a wire. Another conventional bonding pad comprises a top metallayer filling a lattice trench of an inter-dielectric layer forsurrounding dielectric islands. A passivation layer is also formed onthe top metal layer to expose a predetermined bonding area for formingan aluminum pad, thus allowing a ball to be bonded on the aluminum pad.

The above-described bonding pads, however, have the followingdisadvantages. During wafer sorting, wire bonding or probe pin testing,applied forces or large mechanical stresses may crack theinter-dielectric layer adjacent to a probe pin region. Second, the crackmay extend into the interior of the inter-dielectric layer surroundingthe top metal layer, causing corrosion and layer-open problems. Thisalso causes the aluminum pad to peel from the top metal layer, thus thepad-open problem causes the wire to lose contact with the aluminum pad,decreasing bonding reliability. Additionally, the pitch and size of thebonding pad cannot be further shrinked as the bonding pad is susceptibleto damage from the mechanical stress, thus limiting chip size reductionin next generation technologies. Fourth, during wire bonding, a highdistribution ratio of the independent metal plugs or the dielectricislands may create a pad finding issue.

As disclosed in U.S. Pat. No. 6,566,752, another conventional bondingpad comprises a top metal ring formed in a trench of an inter-dielectriclayer. A passivation layer with a plurality of via holes is formed onthe inter-dielectric layer to expose the top metal ring. An aluminum padis formed on the passivation layer and is electrically connected to thetop metal ring through via holes. However, the width of the top metalring is limited by the via hole design, resulting in a misalignmentproblem during photolithography, which prohibits bonding pad fabricationwithin active areas.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a topmetal layer design for a bonding pad structure to obtain a metal-freearea or a small metal area under a metal pad within a sensing region.

According to the object of the invention, a bonding pad structurecomprises a substrate having a bonding region and a sensing region. Afirst dielectric layer is formed overlying the substrate and has adielectric island surrounded by a ring-shaped trench. A first conductivelayer is formed in the ring-shaped trench of the first dielectric layer.A passivation layer is formed overlying the first dielectric layer andhas an opening, in which the opening corresponds to the bonding regionand the sensing region and exposes the dielectric island and a part ofthe first conductive layer. A second conductive layer covers the openingof the passivation layer and is electrically connected to the firstconductive layer.

Another object of the present invention is to provide a passivationopening design for a bonding pad structure to protect a top metal layerunder a metal pad within a sensing region.

According to the object of the invention, a bonding pad structurecomprises a substrate having a bonding region and a sensing region. Afirst dielectric layer is formed overlying the substrate and has atrench. A first conductive layer is formed in the trench of the firstdielectric layer. A passivation layer is formed overlying the firstdielectric layer and has an opening corresponding to the bonding region,wherein the passivation layer covers the first conductive layer formedwithin the sensing region. A second conductive layer covers the openingof the passivation layer and is formed overlying the sensing region. Thesecond conductive layer is electrically connected to the firstconductive layer.

DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawings,given by way of illustration only and thus not intended to be limitativeof the present invention.

FIG. 1 is a top view of an individual chip including bonding padstructures of the present invention.

FIG. 2A is a cross-section of a bonding pad structure according to thefirst embodiment of the present invention.

FIG. 2B is a top view of the conductive ring shown in FIG. 2A.

FIG. 3A is a cross-section of another conductive ring underlying theconductive ring.

FIG. 3B is a cross-section of a conductive lattice underlying theconductive ring.

FIG. 3C is a cross-section illustrating a conductive solid underlyingthe conductive ring.

FIGS. 4A˜4F are top views illustrating examples of profile designs forthe conductive ring.

FIGS. 5A˜5F are top views illustrating examples of the profile designsfor the conductive pad.

FIG. 6A is a top view of corner cut portions of the conductive ring.

FIG. 6B is a top view of corner cut portions of the conductive pad.

FIG. 7A is a top view of the conductive ring with a marking notch.

FIG. 7B is a top view of the conductive pad with a marking notch.

FIG. 8A is a top view of the conductive ring with the marking notchesand the corner cut portions.

FIG. 8B is a top view of the conductive pad with the marking notches andthe corner cut portions.

FIG. 9A is a cross-section of a CUP scheme adjacent to the bonding padstructure.

FIG. 9B is a top view of the conductive ring and the CUP scheme shown inFIG. 9A.

FIG. 10A is a cross-section of one example of forming the CUP schemewithout using the buffer layer.

FIG. 11A is a cross-section of a bonding pad structure according to thesecond embodiment of the present invention.

FIG. 11B is a top view of the conductive ring and the passivation layershown in FIG. 11A.

FIG. 12A is a cross-section of the first conductive layer patterned as alattice.

FIG. 12B is a top view of the conductive layer shown in FIG. 12A.

FIG. 13A is a cross-section of the first conductive layer patterned asindependent plugs.

FIG. 13B is a top view of the conductive layer shown in FIG. 13A.

FIG. 14A is a cross-section of the first conductive layer patterned as asolid form.

FIG. 14B is a top view of the conductive layer shown in FIG. 14A.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a top metal layer design for a bondingpad structure to obtain a metal-free area or a small metal area under ametal pad within a sensing region. The present invention additionallyprovides a passivation opening design for a bonding pad structure toprotect a top metal layer under a metal pad within a sensing region. Thepresent invention effectively prevents corrosion in the top metal layerdue to probing, lengthens the bondability window, eliminates cracks inthe under-layer dielectrics, and prevents peeling of the metal pad fromthe under-layer dielectrics. The present invention also improves padfinding capability (pad recognition capability), reduces pad pitch, andallows the bonding pad structures to be located over peripheral circuitareas, active areas, scribe lines or a combination thereof.

FIG. 1 is a top view of an individual chip including bonding padstructures of the present invention. A semiconductor wafer comprisessubstantially isolated chips, and the isolated chip comprises a mainarea 10 defined by first scribe lines 12 extending in a first directionand second scribe lines 14 extending in a second direction. Theindividual chip 10 containing circuitry comprises an active area 16 anda peripheral area 18. A plurality of bonding structures 20 is allowed onthe active area 16, the peripheral area 18, the first scribe line 12,the second scribe line 14, or a combination thereof. The bonding padstructures 20 may be aligned in a single line or staggered to form CUP(circuit under pad) pads.

The bonding pad structures 20 with a top metal layer design and apassivation opening design for obtaining a metal-free area or a smallmetal area under a metal pad within a sensing region are describedbelow.

First Embodiment

The present invention provides a bonding pad structure with a top metallayer design for obtaining a metal-free area or a small metal area undera metal pad within a sensing region.

FIG. 2A is a cross-section of a bonding pad structure according to thefirst embodiment of the present invention. FIG. 2B is a top view of theconductive ring shown in FIG. 2A.

A semiconductor substrate 22 with partially completed integratedcircuits has a bonding region I for bonding a ball or a bump and asensing region II for testing by probe pins or other implement. A firstdielectric layer 24, an next level dielectric of the substrate 22,comprises a ring-shaped trench 25 which correspondingly defines adielectric island 24 a. A first conductive layer 26, an uppermostinterconnection of the substrate 22, fills the ring-shaped trench 25 toserve as a conductive ring 26, thus enclosing the dielectric island 24a. A passivation layer 30 is formed on the first dielectric layer 24,and has an opening 31 corresponding to the bonding region I and thesensing region II, thus exposing the dielectric island 24 a and asufficient area of the conductive ring 26. A second conductive layer 32is patterned on the first dielectric layer 24 and the passivation layer30 within the bonding region I and the sensing region II to serve as aconductive pad 32, in which the conductive pad 32 is directly connectedto the conductive ring 26 without requiring via holes. A bonding element34, such as a ball or a bump, is bonded on the conductive pad 32 withinthe bonding region I. Moreover, a barrier layer 28 is formed on aninterface between the conductive pad 32 and the conductive ring 26 forincreasing adhesion therebetween.

The first dielectric layer 24 may be plasma oxide, HDP (high densityplasma) oxide, dielectric with high resistance to mechanical stress,low-k dielectrics, fluorinated silicate glass (FSG) or silicon-baseddielectrics. The conductive ring 26 may be copper (Cu), aluminum (Al),AlCu alloy, a copper manganese alloy or a copper-containing alloy. Theconductive ring 26 is approximately 1˜50 μm in width and 0.5˜2 μm indepth. Preferably, a measurement ratio R₁ satisfies the formula:R₁=A_(r)/A_(s) and 0≦R₁≦30% , where A_(r) is the area of the conductivering 26 formed within the sensing region II, and A_(s) is the area ofthe sensing region II. The barrier layer 28 may be Ti, TiN, W, WN, Ta,TaN, or a combination thereof. The conductive pad 32 may be aluminum(Al), AlCu alloy or an aluminum-containing alloy. The bonding element 34may be a gold ball used in wire bonding technology or a metal bump usedin a flip chip technology.

In accordance with the top metal layer design, the conductive ring 26occupies a small area of the sensing region II to achieve a metal-freearea or a small metal area, thus overcoming problems caused by theconventional bonding pads and obtains the following advantages. Themetal-free area or the small metal area effectively reduces thepossibility of cracks penetrating the first dielectric layer 24 to theconductive ring 26, thus preventing corrosion and layer-open problems.The metal-free or small metal area prevents peeling of the conductivepad 32 from the conductive ring 26 or the first dielectric layer 24,thus eliminating pad-open problems and ensuring bonding reliability.Additionally, the pitch and size of the bonding pad structure 20 can befurther reduced since the conductive ring 26 is not susceptible todamage from mechanical stress, thus allowing reduction in chip size fornext generation technologies. The pad finding capability of the wirebonding tool is effectively improved as only one smooth dielectricisland 24 a is enclosed by the conductive ring 26. Finally, since theconductive ring 26 is directly connected to the conductive pad 32without use of via holes or plugs, limitation in ring width andmisalignment problems caused by a via hole design are eliminated, andvarious modifications of the conductive ring 26 and the conductive pad32 are allowed.

Various modifications of the conductive ring 26 and the conductive pad32 are herein described.

FIRST EXAMPLE

Based on design requirements of the top metal layer, theinterconnections underlying the conductive ring 26 may be modified tohave a ring, lattice, island, or solid profile.

FIG. 3A is a cross-section of another conductive ring underlying theconductive ring 26. Elements similar to those in FIG. 2A are omittedhere. A second dielectric layer 36 underlying the first dielectric layer24 is provided. A third conductive layer 38 is patterned as a ring andembedded in the second dielectric layer 36. A conductive plug 40 is alsoformed in the second dielectric layer 36 to electrically connect theconductive ring 26 to the second conductive layer 38.

FIG. 3B is a cross-section of a conductive lattice underlying theconductive ring 26. Elements similar to those in FIG. 3A are omittedhere. The third conductive layer 38 is modified to form a lattice, inwhich an array of dielectric islands 36 a is provided and the dielectricislands 36 are spaced apart from each other by the third conductivelayer 38. Alternately, the third conductive layer 38 is modified to forman array of independent plugs spaced apart from each other by the seconddielectric layer 36.

FIG. 3C is a cross-section illustrating a conductive solid underlyingthe conductive ring 26. Elements similar to those in FIG. 3A are omittedhere. The third conductive layer 38 is modified to have a solid form.

SECOND EXAMPLE

Based on the design requirements of the top metal layer, the conductivering 26, the conductive pad 32, or a combination thereof may be furthermodified to have various geometric shapes.

FIGS. 4A˜4F are top views illustrating examples of profile designs forthe conductive ring 26. FIGS. 5A˜5F are top views illustrating examplesof the profile designs for the conductive pad 32.

The conductive ring 26 is a quadrilateral ring, and the correspondingdielectric island 24 a is a quadrilateral solid. In FIG. 4A, theconductive ring 26 is a square ring, and the corresponding dielectricisland 24 a is a square solid. In FIG. 4B, the conductive ring 26 is arectangular ring, and the corresponding dielectric island 24 a is arectangular solid.

The conductive ring 26 is a circular ring, and the correspondingdielectric island 24 a is a circular solid. In FIG. 4C, the conductivering 26 is a circular ring, and the corresponding dielectric island 24 ais a circular solid. In FIG. 4D, the conductive ring 26 is an ellipticalring, and the corresponding dielectric island 24 a is an ellipticalsolid.

The conductive ring 26 is a polygonal ring, and the correspondingdielectric island 24 a is a polygonal solid. In FIG. 4E, the conductivering 26 is a hexagonal ring, and the corresponding dielectric island 24a is a hexagonal solid. In FIG. 4F, the conductive ring 26 is anoctagonal ring, and the corresponding dielectric island 24 a is anoctagonal solid.

The conductive pad 32 may only be shaped into a geometric solid if theelectrical connection between the conductive pad 32 and the conductivering 26 is reliable. In FIG. 5A, the conductive pad 32 is a squaresolid. In FIG. 5B, the conductive pad 32 is a rectangular solid. In FIG.5C, the conductive pad 32 is a circular solid. In FIG. 5D, theconductive pad 32 is an elliptical solid. In FIG. 5E, the conductive pad32 is a hexagonal solid. In FIG. 5F, the conductive pad 32 is anoctagonal solid.

THIRD EXAMPLE

Based on a quadrilateral design for the conductive ring 26 or theconductive pad 32, at least one corner cut portion is provided toprevent peeling.

FIG. 6A is a top view of corner cut portions of the conductive ring 26.FIG. 6B is a top view of corner cut portions of the conductive pad 32.Elements similar to those in FIG. 2B are omitted here.

In FIG. 6A, the conductive ring 26 comprises four corner cut portions 42adjacent to four corners of the quadrilateral ring, respectively. Thecorner cut portion 42 prohibits the formation of the first conductivelayer 26, but allows the formation of the first dielectric layer 24.Preferably, the corner cut portion 42 is a right triangle, where thehypotenuse 41 is approximately 0.5˜5 μm in length, an included angle θ₁between the hypotenuse 41 and the X axis is approximately 10°˜80°, and ameasurement ratio R₂ satisfies the formula: R₂=A_(t1)/A_(c1) and0<R₂<80%, where A_(t1) is the area of the corner cut portion 42, andA_(c1) is the corner area of the conductive ring 26. The corner areaA_(c1) satisfies the formula: A_(c1)=W₁×W₂, where W₁ is the X-axis widthof the conductive ring 26, W₂ is the Y-axis width of the conductive ring26, W₁=1 μm˜10 μm, and W₂=1 μm˜10 μm.

In FIG. 6B, the conductive pad 32 comprises four corner cut portions 44adjacent to four corners of the quadrilateral solid, respectively. Thecorner cut portion 44 prohibits the formation of the second conductivelayer 32, but allows the formation of the passivation layer 30.Preferably, the corner cut portion 44 is a right triangle, where thehypotenuse 43 is approximately 0.5˜10 μm in length, and an includedangle θ₂ between the hypotenuse 41 and the X axis is approximately10°˜80°.

FOURTH EXAMPLE

In order to clearly discriminate the sensing region II from the bondingregion I, a marking notch is provided on the conductive ring 26, theconductive pad 32, or a combination thereof.

FIG. 7A is a top view of the conductive ring 26 with a marking notch.FIG. 7B is a top view of the conductive pad 32 with a marking notch.Elements similar to those in FIG. 2B are omitted here.

In FIG. 7A, the conductive ring 26 comprises two marking notches 46, andtwo dielectric markings 24 b are correspondingly defined within the twomarking notches 46, respectively. The two marking notches 46 areapproximately aligned in a line to delineate the sensing region II fromthe bonding region I. Each of the two marking notches 46 is composed ofa bottom side 46I and two lateral sides 46II. Preferably, afirst-direction length L₁ from the lateral side 46II to the edge of theconductive ring 26 for defining the bonding region I is approximately40˜60 μm. Preferably, a first length S₁ of the dielectric marking 24 b,parallel to the bottom side 46I, is approximately 1˜3 μm. Preferably, asecond length S₂ of the dielectric marking 24 b, parallel to the lateralside 46II, is approximately 0.5˜2 μm.

In FIG. 7B, the conductive pad 32 comprises two marking notches 48, andtwo passivation markings 30 b are correspondingly defined within the twomarking notches 48, respectively. The two marking notches 48 areapproximately aligned in a line to delineate the sensing region II fromthe bonding region I. Each of the two marking notches 48 is composed ofa bottom side 48I and two lateral sides 48II. Preferably, afirst-direction length L₁ from the lateral side 48II to the edge of theconductive pad 32 for defining the bonding region I is approximately40˜60 ∞m. Preferably, a first length S₁ of the passivation marking 30 b,parallel to the bottom side 48I, is approximately 1˜3 μm. Preferably, asecond length S₂ of the passivation marking 30 b, parallel to thelateral side 48II, is approximately 0.5˜2 μm.

Additionally, the marking notch design for the conductive ring 26 andthe conductive pad 32 can be combined with the corner cut designs asdescribed in FIGS. 6A and 6B.

FIG. 8A is a top view of the conductive ring 26 with the marking notches46 and the corner cut portions 42. FIG. 8B is a top view of theconductive pad 32 with the marking notches 48 and the corner cutportions 44. Elements similar to those in FIGS. 6˜7 are omitted here.

FIFTH EXAMPLE

Based on the design requirements of the top metal layer, a circuit underpad (CUP) scheme can be further provided under an extension portion theconductive ring 26. Locating the circuit under the pad shortens some ofthe conductors and thereby decreases their inductance and resistance andalso reduces the parasitic capacitance of the circuit.

FIG. 9A is a cross-section of a CUP scheme 50 adjacent to the bondingpad structure 20. FIG. 9B is a top view of the conductive ring 26 andthe CUP scheme 50 shown in FIG. 9A. Elements similar to those in FIGS.6˜7 are omitted here.

The conductive ring 26 comprises an extension portion 26 a which extendsfrom one peripheral edge of the conductive ring 26 and away from thebonding region I and the sensing region II. A CUP scheme 50 is formedadjacent to the extension portion 26 a. A buffer layer 52 is formedunderneath the first dielectric layer 24 and has a circuit scheme 54patterned therein. A plurality of conductive plugs 56 is formed in anarray of via holes 57 of the first dielectric layer 24. Thus, theextension portion 26 a can be electrically connected to the circuitscheme 54 through via holes 57. Also, the circuit scheme 54 can beelectrically connected to a lowermost conductive layer 58 throughinterconnections. Preferably, the number of via holes 57 for a signalcircuit scheme is smaller than that for a power circuit scheme.

In addition, based on a combination of the conductive ring 26 and theCUP scheme 50, the buffer layer 52 may be optional, and the conductivelayers underlying the conductive ring 26 may be modified.

FIG. 10A is a cross-section of one example of forming the CUP scheme 50without using the buffer layer 52. Elements similar to those in FIG. 9Aare omitted here. The different portion is that the buffer layer 52 isomitted, thus the circuit scheme 54 is formed in the first dielectriclayer 24.

FIG. 10B is a cross-section of another example of forming the CUP scheme50 underneath two conductive rings. Elements similar to those in FIG. 9Aare omitted here. The different portion is that the third conductivelayer 38 is patterned as a ring and embedded in the second dielectriclayer 36, and is electrically connected to the conductive ring 26through the conductive plug 40. Also, the third conductive layer 38 hasan extension portion 38 a which extends from one peripheral edge of thering to be electrically connected to the circuit scheme 54 through viaholes 57.

Second Embodiment

The present invention provides a bonding pad structure with apassivation opening design for protecting a top metal layer within asensing region.

FIG. 11A is a cross-section of a bonding pad structure according to thesecond embodiment of the present invention. FIG. 11B is a top view ofthe conductive ring 26 and the passivation layer 30 shown in FIG. 11A.

A semiconductor substrate 22 with partially completed integratedcircuits has a bonding region I for bonding a ball or a bump and asensing region II for testing by probe pins or other implement. A firstdielectric layer 24, an uppermost dielectric of the substrate 22,comprises a ring-shaped trench 25 which correspondingly defines adielectric island 24 a. A first conductive layer 26, an uppermostconductive layer of interconnections in the substrate 22, fills thering-shaped trench 25 to serve as a conductive ring 26, thus enclosingthe dielectric island 24 a. A passivation layer 30 is formed on thefirst dielectric layer 24, and has an opening 31 corresponding to thebonding region I, thus covering the conductive ring 26 located withinthe sensing region II. A second conductive layer 32 is formed overlyingthe first dielectric layer 24 and the passivation layer 30 within thebonding region I and the sensing region II to serve as a conductive pad32, in which the conductive pad 32 is directly connected to theconductive ring 26 without requiring via holes. A bonding element 34,such as a ball or a bump, is bonded to the conductive pad 32 within thebonding region I. Moreover, a barrier layer 28 is provided on aninterface between the conductive pad 32 and the conductive ring 26.

Preferably, the first dielectric layer 24 may be plasma oxide, HDP (highdensity plasma) oxide, dielectric with high resistance to mechanicalstress, low-k dielectrics, FSG, or silicon-based dielectrics. Theconductive ring 26 may be copper (Cu), aluminum (Al), AlCu alloy, acopper manganese alloy or a copper-containing alloy. The conductive ring26 is approximately 1˜50 μm in width and 0.5˜2 μm in depth. The barrierlayer 28 may be Ti, TiN, W, WN, Ta, TaN, or a combination thereof. Theconductive pad 32 may be aluminum (Al), AlCu alloy or analuminum-containing alloy. The bonding element 34 may be a gold ballused in wire bonding technology or a metal bump used in a flip chiptechnology.

Accordingly, the passivation layer 30 covers the conductive ring 26within the sensing region II to prevent damage to the conductive ring 26within the sensing region caused by mechanical stress. The passivationlayer 30 adjacent to the demarcation between the bonding region I andthe sensing region II can also serve as a marking strip, which has thesame function of the marking notches as described in FIGS. 7A and 7B. Inaddition, other interconnections underlying the conductive ring 26 maybe modified to have a ring, lattice, island, or solid profile asdisclosed in FIGS. 3A˜3C.

The passivation opening design for the passivation layer 30 achieves thefollowing advantages. The passivation layer 30 covers the conductivering 26 within the sensing region II to prohibit dielectric cracks frompenetrating into the conductive ring 26, thus preventing corrosion andlayer-open problems. The passivation layer also prevents peeling of theconductive pad 32 from the conductive ring 26 or the first dielectriclayer 24, thus eliminating a pad-open problem and ensuring bondingreliability. The pitch and size of the bonding pad structure 20 can befurther reduced since the conductive ring 26 is not susceptible todamage from mechanical stress, thus allowing chip size reduction fornext generation technologies. The pad finding capability can beeffectively improved during wire bonding as only one dielectric island24 a is enclosed by the conductive ring 26. Finally, the conductive ring26 is directly connected to the conductive pad 32 without use of viaholes or plugs, thus limitation in ring width and misalignment problemscaused by via hole design are eliminated, enabling various modificationsof the conductive ring 26 and the conductive pad 32.

Various modifications of the conductive ring 26 and the conductive pad32 are herein described.

FIRST EXAMPLE

Based on the passivation opening design rule, the first conductive layer26 may be further modified to have a lattice form or as independentplugs.

FIG. 12A is a cross-section of the first conductive layer 26 patternedas a lattice form. FIG. 12B is a top view of the first conductive layer26 shown in FIG. 12A. Elements similar to those in FIGS. 11A and 11B areomitted here. The first dielectric layer 24 comprises a plurality ofdielectric islands 24 a. The first conductive layer 26 fill the trenchesof the first dielectric layer 24 to completely surround the dielectricislands 24 a, thus achieving a lattice form.

FIG. 13A is a cross-section of the first conductive layer 26 patternedas independent plugs. FIG. 13B is a top view of the first conductivelayer 26 shown in FIG. 13A. Elements similar to those in FIGS. 11A and11B are omitted here. The first dielectric layer 24 comprises aplurality of via holes. The first conductive layer 26 fills the viaholes of the first dielectric layer 24 to form a plurality ofindependent plugs 26. Additionally, the independent plugs 26 can beelectrically connected to each other through a third conductive layer 38underlying the plugs 26.

Other interconnections underlying the first conductive layer 26 may alsobe modified to have a ring, lattice, island, or solid profile asdisclosed in FIGS. 3A˜3C.

SECOND EXAMPLE

Based on the passivation opening design rule, the first conductive layer26 may be further modified to have a solid form.

FIG. 14A is a cross-section of the first conductive layer 26 patternedas a solid form. FIG. 14B is a top view of the first conductive layer 26shown in FIG. 14A. Elements similar to those in FIGS. 11A and 11B areomitted here. The first conductive layer 26 fills a large-size trench ofthe first dielectric layer 24 to become a solid form. In addition, otherinterconnections underlying the first conductive layer 26 may bemodified to have ring, lattice, island, or solid profiles as disclosedin FIGS. 3A˜3C.

THIRD EXAMPLE

Based on the passivation opening design rule, the first conductive layer26, the conductive pad 32 or a combination thereof may be furthermodified to have various profiles including quadrilateral, circular andpolygonal profiles as described in FIGS. 4A˜4F and FIGS. 5A˜5F. Featuressimilar to those in FIGS. 4˜5 are omitted here.

FOURTH EXAMPLE

Based on the passivation opening design rule, the first conductive layer26, the conductive pad 32 or a combination thereof may be furthermodified with at least one corner cut portion as described in FIGS. 6Aand 6B. Features similar to those in FIGS. 6A and 6B are omitted here.

FIFTH EXAMPLE

Based on the passivation opening design rule, the first conductive layer26, the conductive pad 32 or a combination thereof may be furthermodified with a marking notch as described in FIGS. 7A and 7B and FIGS.8A and 8B. Features similar to those in FIGS. 7˜8 are omitted here.

SIXTH EXAMPLE

Based on the passivation opening design rule, a circuit under pad (CUP)scheme 50 can be provided under an extension portion 26 a the firstconductive layer 26 as described in FIGS. 9˜10. Features similar tothose in FIGS. 9˜10 are omitted here.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

1. A bonding pad structure, comprising: a substrate having a bondingregion and a sensing region; a first dielectric layer formed overlyingthe substrate and having a trench; a first conductive layer formed inthe trench of the first dielectric layer; a passivation layer formedoverlying the first dielectric layer and having an opening correspondingto the bonding region, wherein the opening exposes the first dielectriclayer and a part of the first conductive layer, the passivation layercovers the first conductive layer formed within the sensing region; anda second conductive layer covering the opening of the passivation layerand formed overlying the sensing region, wherein the second conductivelayer is electrically connected to the first conductive layer.
 2. Thebonding pad structure as claimed in claim 1, wherein the substratefurther comprises: a main area comprising an active area and aperipheral area; a first scribe line extending along a first direction;and a second scribe line extending along a second direction, wherein theintersection of the first scribe line and the second scribe line definesthe main area; wherein, the bonding pad structure is formed overlyingthe active area, the peripheral area, the first scribe line, the secondscribe line or a combination thereof.
 3. The bonding pad structure asclaimed in claim 2, wherein the bonding pad structures are arranged in asingle line or staggered.
 4. The bonding pad structure as claimed inclaim 1, wherein the width of the first conductive layer is 1˜50 μm. 5.The bonding pad structure as claimed in claim 1, wherein the depth ofthe first conductive layer is 0.5˜2 μm.
 6. The bonding pad structure asclaimed in claim 1, wherein the first conductive layer is a ring, alattice form, an array of islands or a solid form.
 7. The bonding padstructure as claimed in claim 1, wherein the trench of the firstdielectric layer is a ring, a lattice form, an array of islands or asolid form.
 8. The bonding pad structure as claimed in claim 1, furthercomprising: a second dielectric layer formed underlying the firstdielectric layer; a third conductive layer formed in the seconddielectric layer; and at least one conductive plug formed in the seconddielectric layer and electrically connecting the third conductive layerto the first conductive layer.
 9. The bonding pad structure as claimedin claim 8, wherein the third conductive layer is a ring, a latticeform, an array of islands or a solid form.
 10. The bonding pad structureas claimed in claim 1, wherein the second conductive layer is aquadrilateral solid, a circular solid, a hexagonal solid, an octagonalsolid or a polygonal solid.
 11. The bonding pad structure as claimed inclaim 1, further comprising at least one corner cut portion adjacent toat least one corner of the first conductive layer, wherein the cornercut portion prohibits the formation of the first conductive layer andallows the formation of the first dielectric layer.
 12. The bonding padstructure as claimed in claim 11, wherein the corner cut portion is aright triangle, the hypotenuse length of the right triangle is 0.5˜5 μm,and an included angle θ₁ between the hypotenuse and X axis is 10°˜80°.13. The bonding pad structure as claimed in claim 11, wherein ameasurement ratio R₂ satisfies the formula: R₂=A_(t1)/A_(c1),A_(c1)=W₁×W₂, and 0<R₂<80%, where A_(t1) is the area of the corner cutportion, A_(c1) is the corner area of the first conductive layer, W₁ isa first-direction width of the corner area of the first conductive layeris a second-direction width of the corner area of the first conductivelayer.
 14. The bonding pad structure as claimed in claim 1, furthercomprising at least one corner cut portion adjacent to at least onecorner of the second conductive layer, wherein the corner cut portionprohibits the formation of the second conductive layer and allows theformation of the passivation layer.
 15. The bonding pad structure asclaimed in claim 14, wherein the corner cut portion is a right triangle,the hypotenuse length of the right triangle is 0.5˜10 μm, and anincluded angle θ₁ between the hypotenuse and X axis is 10°˜80°.
 16. Thebonding pad structure as claimed in claim 1, wherein the firstconductive layer further comprises at least one marking notch whichdiscriminates the sensing region from the bonding region.
 17. Thebonding pad structure as claimed in claim 16, wherein the marking notchof the first conductive layer comprises a bottom side and two lateralsides which surround the first dielectric layer to define a dielectricmarking.
 18. The bonding pad structure as claimed in claim 17, wherein afirst length of the dielectric marking parallel to the bottom side ofthe marking notch is 1˜3 μm, and a second length of the dielectricmarking parallel to the lateral side of the marking notch is 0.5˜2 μm.19. The bonding pad structure as claimed in claim 1, wherein the secondconductive layer further comprises at least one marking notch whichdiscriminates the sensing region from the bonding region.
 20. Thebonding pad structure as claimed in claim 19, wherein the marking notchof the second conductive layer comprises a bottom side and two lateralsides which surround the passivation dielectric layer to define apassivation marking.
 21. The bonding pad structure as claimed in claim20, wherein a first length of the passivation marking parallel to thebottom side of the marking notch is 1˜3 μm, and a second length of thepassivation marking parallel to the lateral side of the marking notch is0.5˜2 μm.
 22. The bonding pad structure as claimed in claim 1, furthercomprising: an extension portion of the first conductive layer extendingaway from the bonding region and the sensing region; and a circuit underpad (CUP) scheme formed underlying the extension portion of the firstconductive layer.
 23. The bonding pad structure as claimed in claim 22,wherein the circuit under pad (CUP) scheme comprises: a circuit schemeformed underlying the extension portion of the first conductive layer;and a plurality of conductive plugs electrically connecting the circuitscheme to the extension portion of the first conductive layer.
 24. Thebonding pad structure as claimed in claim 23, wherein the circuit underpad (CUP) scheme comprises: a buffer layer formed underlying the firstdielectric layer, wherein the circuit scheme is formed in the bufferlayer; and a plurality of via holes formed in the first dielectric layerand underlying the extension portion of the first conductive layer,wherein the conductive plugs are formed in the via holes respectively.25. The bonding pad structure as claimed in claim 23, wherein thecircuit under pad (CUP) scheme comprises: a plurality of via holesformed in the first dielectric layer and underlying the extensionportion of the first conductive layer, wherein the conductive plugs areformed in the via holes respectively; and wherein the circuit scheme isformed in the first dielectric layer and underlying the conductiveplugs.
 26. The bonding pad structure as claimed in claim 22, wherein thecircuit under pad (CUP) scheme comprises: a second dielectric layerformed underlying the first dielectric layer; a third conductive layerformed in the second dielectric layer and electrically connected to thefirst conductive layer; an extension portion of the third conductivelayer extending away from the bonding region and the sensing region; abuffer layer formed underlying the second dielectric layer; a circuitscheme formed in the buffer layer; and a plurality conductive plugselectrically connecting the circuit scheme to the extension portion ofthe third conductive layer.
 27. The bonding pad structure as claimed inclaim 26, wherein the third conductive layer is a ring, a lattice form,an array of islands or a solid form.
 28. The bonding pad structure asclaimed in claim 1, further comprising a bonding element formedoverlying the second conductive layer within the bonding region.
 29. Thebonding pad structure as claimed in claim 28, wherein the bondingelement is a conductive ball or a conductive bump.
 30. The bonding padstructure as claimed in claim 1, further comprising a barrier layerformed between the first conductive layer and the second conductivelayer.
 31. The bonding pad structure as claimed in claim 30, wherein thebarrier layer is Ti, TiN, W, WN, Ta, TaN or a combination thereof. 32.The bonding pad structure as claimed in claim 1, wherein the firstconductive layer is copper (Cu), aluminum (Al), AlCu alloy, a coppermanganese alloy, or a copper-containing alloy.
 33. The bonding padstructure as claimed in claim 1, wherein the second conductive layer isaluminum (Al), AlCu alloy or an aluminum-containing alloy.
 34. Thebonding pad structure as claimed in claim 1, wherein the firstdielectric layer is plasma oxide, HDP oxide, dielectric with highresistance to mechanical stress, low-k dielectrics, fluorinated silicateglass (FSG) or silicon-based dielectrics.